A number of devices are currently available for harvesting living bone tissue for reparative bone grafting procedures. Certain of these devices involve a manual scraping of bone from either the jaw or iliac crest of the hip of the patient. Significant portions of bone must be exposed in order to permit the necessary scraping motion. Other devices involve the use of a drill to create the bone fragments, then the collection of the particles by a secondary operation involving a different tool. Yet a third device involves carving out a window in the bone and introducing the harvested material into a table top grinder to morselize the fragment into particles of appropriate size. A fourth device, called a trephine or coring drill removes a plug and in a secondary operation, grinds the plug to the desired particle size.
It is an object of the present invention to overcome the deficiencies of the prior art by providing a single device which can harvest, morselize, collect and deliver bone particles to a reparative site in a single continuous procedure while requiring only a minimally invasive incision. In addition, an alternate cap and filter screen can be utilized to convert the system for collecting morselized fragments created by a previous drilling operation.
The bone harvesting, collection, and delivery system of the present invention includes a rotary drill bit adapted for attachment to a rotary surgical power tool. The drill bit preferably has a tip angle of 90.degree. for maximum bone penetration and edges of the tip to cut and morselize the bone as the drill bit penetrates the designated area. The collection reservoir for collecting bone chips harvested by the drill bit includes an elongated body member and a removable top, said elongated body member having a tubular cannula portion which serves as a cylindrical guide for said drill bit and an enlarged chamber portion which receives the morselized bone fragments.
A suction port extends through said removable top into the enlarged chamber portion such that suction can be applied to a harvest site through said enlarged chamber portion and said tubular cannula portion so that bone fragments and irrigation fluid are removed from the harvest site by being drawn into a distal end of said tubular cannula portion. A fine mesh filter screen located in said collection reservoir filters the bone fragments from the irrigation fluid, the bone fragments being retained in said collection reservoir as the irrigation fluid is removed through said suction port. A retention plug may be inserted in said distal end of the tubular cannula portion to retain the bone fragments in the collection reservoir after said bone fragments have been harvested.
A plunger which can be inserted into said a top portion of the collection reservoir to eject said harvested bone fragments from said distal end of said tubular cannula portion into a reparation region. Preferably, the cap has threads which are on an external portion of its periphery which engage inwardly projecting threads of said collection reservoir. In this way, the cap has a profile which is no greater than that of the collection reservoir. The body and top of the reservoir are preferably made of a biocompatible material selected from the group consisting of titanium, alloys of titanium and a sturdy plastic material. Plastic is most preferable, since the use of a transparent or translucent plastic material will enable a visual determination of completion of the collection process without the need to remove the cap from the body of the collection reservoir.
A safety feature of the present device is that the depth of cut is limited. The cap has a guide tube which extends upwardly toward the power tool. The guide tube steadies the drill bit during its operation and, in addition, a leading end of the guide tube serves to stabilize the filter screen against the pull of the suction. The length of the drill bit and the bottoming out of the power tool against the top of the guide tube serve to limit the penetration depth of the drill bit. Preferably, the device will be sold with several lengths of drill bits since, for example, the penetration desired for harvesting from a jaw bone will generally be different from the penetration desired when harvesting from an iliac crest of a hip bone.
A collection cap equipped with a large suction port may supplant said harvesting cap and its drill bit to enable collection of bone fragments harvested by an earlier drilling operation. A collection wand is insertable into said distal end of said tubular cannula portion to enable collecting of bone fragments from such a harvest site. The collection wand has an angled portion proximate said distal end to facilitate insertion into a harvest site. The collection cap and wand can be removed and the plunger utilized to deliver bone fragments to the restoration site as was done with the earlier configuration.
Various other features, advantages and characteristics of the present invention will become apparent to one of ordinary skill in the art after a reading of the following specification.